DE202017107779U1 - LED driver - Google Patents

Abstract

An LED driver, at least comprising:
a rectifier circuit comprising a first AC input terminal, a second AC input terminal, a first rectifier output terminal and a second rectifier output terminal, the first and second AC input terminals for receiving an AC input power, the rectifier circuit having at least four unidirectional components, namely, the first, second, third, and fourth unidirectional components, wherein the positive terminals of the first and third unidirectional components are respectively connected to the first and second AC input terminals, the negative terminals of the first and fourth unidirectional components being respectively connected to the first and second unidirectional components the second rectifier output terminal is connected, the negative terminal of the second and third unidirectional components being connected to the first rectifier output terminal, respectively;
a first LED module connected between the negative terminal of the first unidirectional component and the positive terminal of the second unidirectional component;
a second LED module connected between the negative terminal of the third unidirectional component and the positive terminal of the fourth unidirectional component; and
a multi-stage driver module connected between the positive terminal of the second unidirectional component and the positive terminal of the fourth unidirectional component.

Description

Field of the invention

The present invention relates to an LED driver and driving method thereof in which the brightness difference between different LED modules can be reduced by a simple circuit structure, and thus the problem of the uneven brightness can be eliminated.

State of the art

Light-emitting diodes (LEDs) are electronic semiconductor components that have the ability to shine. Such electronic components have been around since 1962. Initially, they could emit only weak red light, and later they were further developed to be used as other monochromatic light sources. Today, LEDs can emit all the visible light, infrared light and UV light, and their luminosity has increased significantly. In the initial phase, LEDs were used as indicator lights and scoreboards. With the advent of the white LED, the use of LEDs in various lighting devices has also steadily increased. For example, LEDs with high brightness are widely used in traffic lights, vehicle lights and brake lights. In recent years, lighting devices have also been developed which use a high voltage LED light string to replace conventional white incandescent and fluorescent lamps.

To light LEDs, operation with a DC (Direct Current) power supply is required. When LEDs are used for a lighting or display device and AC (Alternating Current) is used for the lighting or display device, a current transformer circuit is additionally required to convert the AC to DC, then the DC is applied to the LEDs to the LEDs to light up. In today's lighting market, the current LED lamp drivers can be divided into 1. Switch driver, 2. Resistance-capacity driver, 3. Multi-stage linear driver and 4. LED constant current driver. Among them, the switching driver has a complicated configuration, requires a complicated assembly and has a short life, and in addition a dimming circuit has to be added when dimming of the light energy is required, thereby increasing its cost. The voltage and current of the resistance-capacitance driver are unstable. The LED constant current driver has a low efficiency.

1 shows an LED lighting unit having a multi-stage linear driver. Behind the bridge rectifier 110 a LED string of lights is connected, with the LED string of lights in two segments, namely in the first LED segment 121 and the second LED segment 122 is divided, wherein the two LED segments are respectively connected to the corresponding input terminals DR1, DR2 of the multi-stage linear driver IC140 (see simultaneously 2 ). By increasing the input voltage 210 is in an AC cycle on the first LED segment 121 and on the second LED segment 122 successively made an electrically conductive connection, whereby these two shine. When the input voltage 210 is small, the multi-stage linear driver IC140 is powered via the input terminal DR1, wherein the input terminal DR1 an electrically conductive connection is made. When the input voltage 210 up to the illumination voltage of the first LED segment 121 is increased, at this time on the first LED segment 121 made an electrically conductive connection, whereby this lights up, wherein the input terminal DR1 starts to work and the LED current I1 flows through the input terminal DR1. When the input voltage 210 is further increased such that the voltage drop of the input terminal DR1 with respect to the input terminal DR2, the illumination voltage of the second LED segment 122 achieved is at this time on the first LED segment 121 and on the second LED segment 122 made an electrically conductive connection, whereby the first and second LED segment light up, wherein the LED current I2 flows through the input terminal DR2 and the input terminal DR1 is closed. In the opposite case, the second LED segment work 122 and the first LED segment 121 with the decrease of the input voltage 210 when the voltage drops below the illumination voltage of all LED segments, not one after the other. Therefore, by using such a multi-stage linear driver without additional dimming circuit, a dimming function can be achieved.

From the 2 it can be seen that by increasing the input voltage 210 in a flow path of the positive and negative half cycle of the AC cycle in the process, in the same order on the first LED segment 121 and on the second LED segment 122 successively an electrically conductive connection is made and these two light up (the first LED segment 121 always lights first and then the second LED segment lights up 122 ), the time they take to light up and their performance are different. This causes the two LED segments 121 . 122 have different amounts of light and thus the problem of uneven brightness between the two LED segments occurs. To solve this problem, it is required as disclosed in the Taiwanese Patent Application Publication TW 201104915 A It is known to arrange all the LEDs in a complicated manner, so that the LEDs in different segments of the LED string of lights can be evenly distributed so as to avoid a brightness difference caused by the different cycles of the different segments. However, such a design not only complicates the design of the LED lamps, but also leads to the necessity of using a LED string of lights having a large number of LEDs.

During operation, deviations also occur in all LEDs in synchronism with the sine wave of the power supply. Ie. Over time, there is a rapid, repetitive change in the intensity of the light emitted by the respective LEDs, causing the light sources to flicker and be unstable, i. e. H. the phenomenon of flicker occurs. Irrespective of whether the human eye is able to perceive it or not, the phenomenon of flickering has a negative impact on the human body to varying degrees. Headache, dizziness, eye pain, nervousness or even epilepsy.

• 1. Wenn der Kondensator am ersten LED-Segment 121 angeordnet ist, werden in der Ladephase die LEDs mit Wechselstrom angetrieben und der Kondensator wird gleichzeitig geladen. In der Entladephase werden die LEDs durch den Kondensator mit Strom versorgt. Zu diesem Zeitpunkt kann zwar das Problem des Flimmerns des ersten LED-Segments 121 gelöst und die Lichtausbeute verbessert werden, allerdings vergrößert sich in einem AC-Zyklus der Unterschied zwischen dem ersten LED-Segment 121 und dem zweiten LED-Segment 122, wodurch das Problem der ungleichmäßigen Helligkeit gravierender wird.
• 2. Wenn die beiden LED-Segmente 121, 122 mit einem Kondensator parallel geschaltet sind, kann die Eingangsspannung zwar fest auf die Beleuchtungsspannung des zweiten LED-Segments 122 eingestellt werden, jedoch wird zu diesem Zeitpunkt am ersten LED-Segment 121 und am zweiten LED-Segment 122 eine elektrisch leitende Verbindung hergestellt, wodurch diese beiden gleichzeitig leuchten, womit die Wirkung des mehrstufigen Antreibens verloren geht.
• 3. Wenn der Kondensator mit dem Gleichrichterausgangsanschluss verbunden ist, kann zwar der AC-Spannungsausgang nach der Gleichrichtung derart eingestellt werden, dass eine stabile Wechselstromspannung erzeugt wird, jedoch kommt es durch den starken Anstieg und den linearen Abfall des Wechselstroms und durch den hohen Grad der harmonischen Verzerrung der Wellenform zu einer niedrigen Leistung der LED-Beleuchtungseinheit. Ferner muss der Spannungsfestigkeitswert des Kondensators höher als die Eingangsspannung sein. Wenn beispielsweise die Eingangsspannung 110 Volt beträgt, muss für den Kondensator ein Hochspannungskondensator verwendet werden (dessen Spannungsfestigkeitswert beträgt 150 Volt). Allerdings führt der Einsatz von Hochspannungskondensatoren auch zu einer relativen Erhöhung der Kosten und der Größe.

In general, in the drive circuit for adjusting the AC voltage output of the rectifier and generating a stable DC voltage, the capacitance is increased to obtain the effect of stable voltage and to improve the phenomenon of flicker. However, increasing the capacity of the LED lighting unit of the above-mentioned multi-stage linear driver is not a well-suited method. The reasons for this are described below:

• 1. If the capacitor is on the first LED segment 121 is arranged, the LEDs are driven with alternating current in the charging phase and the capacitor is charged simultaneously. In the discharge phase, the LEDs are powered by the capacitor. Although at this time may be the problem of flickering the first LED segment 121 solved and the light output can be improved, however, increases in an AC cycle, the difference between the first LED segment 121 and the second LED segment 122 , whereby the problem of uneven brightness becomes more serious.
• 2. If the two LED segments 121 . 122 Although connected in parallel with a capacitor, the input voltage can be fixed to the illumination voltage of the second LED segment 122 However, at this time, the first LED segment will be set 121 and on the second LED segment 122 made an electrically conductive connection, whereby these two light up simultaneously, whereby the effect of the multi-stage driving is lost.
• 3. When the capacitor is connected to the rectifier output terminal, the rectified AC voltage output can be set to produce a stable AC voltage, but it is caused by the large increase and decrease of the alternating current and the high degree of AC harmonic distortion of the waveform to low power of the LED lighting unit. Furthermore, the withstand voltage value of the capacitor must be higher than the input voltage. For example, if the input voltage is 110 volts, a high voltage capacitor must be used for the capacitor (its withstand voltage value is 150 volts). However, the use of high voltage capacitors also leads to a relative increase in cost and size.

Therefore, there is a need for an LED driver having a relatively simple circuit structure and by which the power and amount of light of all LED segments of the LED string is equal within the cycle time of the AC to avoid the occurrence of uneven brightness, and thus to improve the flicker phenomenon without compromising the performance of the LED driving circuit. In this way, AC powered LED devices are even better suited for use in lighting.

Object of the invention

In view of the above problem, the object of the present invention is to provide an LED driver and a driving method thereof in which the brightness difference between different LED modules can be reduced by a simple circuit structure, and thus the problem of uneven brightness can be solved.

Technical solution

In the present invention, in each case a flow path of the positive or negative half cycle of the alternating current is provided by at least two unidirectional components, wherein in each case in the flow path of the positive or negative half cycle at least two LED modules are integrated and further a multi-stage driver module is integrated, whereby the at least two LED modules, when one electrically conductive connection is made in the positive half-cycle or in the negative half-cycle, light up in a different order so that in the cycle time of the alternating current the power and brightness of the at least two LED modules may be consistent, thereby To significantly reduce the problem of uneven brightness between different LED modules in a common multi-level driver.

The present invention further provides an LED driver comprising at least one rectifier circuit including a first AC input terminal, a second AC input terminal, a first rectifier output terminal, and a second rectifier output terminal, the first and second AC input terminals for receiving an AC Serve the input power, wherein the rectifier circuit is provided with at least four unidirectional components, namely, the first, second, third and fourth unidirectional component, wherein the positive terminal of the first and third unidirectional component is respectively connected to the first and second AC input terminal, wherein the negative terminal of the first and fourth unidirectional components is respectively connected to the second rectifier output terminal, wherein the negative terminal of the second and third unidirectional component is connected to the first rectifier output terminal, respectively connected is; a first LED module connected between the negative terminal of the first unidirectional component and the positive terminal of the second unidirectional component; a second LED module connected between the negative terminal of the third unidirectional component and the positive terminal of the fourth unidirectional component; and a multi-stage driver module connected between the positive terminal of the second unidirectional component and the positive terminal of the fourth unidirectional component.

In the following, the invention will be described in more detail in a schematic representation with reference to the figures.

Brief description of the drawings

Show it

1 a schematic representation of a conventional multi-stage linear driver,

2 a representation of the voltage waveforms within the cycle time of the alternating current of a conventional multi-stage linear driver,

3 a first schematic representation of an LED driver according to the invention,

4 a representation of the voltage waveforms within the cycle time of the alternating current of the LED driver according to the invention,

5 a second schematic representation of an LED driver according to the invention,

6 a third schematic representation of an LED driver according to the invention,

7 a fourth schematic representation of an LED driver according to the invention and

8th a fifth schematic representation of an LED driver according to the invention.

Detailed Description of the Preferred Embodiments

Unless otherwise indicated, the following terms used in the specification and claims have the meanings given below. It should be noted that the singular forms used in the specification and claims are "on";"One" and "the one";"the";"That" also on one or more of the listed items, eg. At least one, at least two or at least three, instead of being able to refer to only a single object. In addition, it should be noted the terms "comprising" and "comprising" as used in the claims should be understood to mean that the components or combination of ingredients described in the claims do not preclude other components or components not described in the claims. It should be noted that the term "or" is inclusive or equivalent to and equivalent to the term "and / or" unless the context clearly dictates otherwise. Insofar as the term "about" is used in the description and claims of the present invention, it is obvious that the stated range limits or values do not represent rigid limits, but rather that the object and purpose of the present invention are fulfilled even with minor deviations.

In the case of the drive method according to the invention, in each case a flow path of the positive or negative half-cycle of the alternating current is provided by at least two unidirectional components, wherein in each case at least two LED modules are integrated in the flow path of the positive or negative half-cycle and further a multi-stage driver module is integrated, whereby the at least two LED modules, if in the positive half-cycle or in the negative half-cycle an electrically conductive connection is made, light up in a different order.

Im in 3 As shown in the first embodiment, the driving method is achieved by using a driver. The driver comprises at least one rectifier circuit, a first LED module 510 , a second LED module 610 and a multi-stage driver module 710 ,

The rectifier circuit includes a first AC input terminal 311 , a second AC input terminal 312 , a first rectifier output terminal 313 and a second rectifier output terminal 314 , wherein the first and second AC input terminals 311 . 312 by rectification to receive AC input power and to convert the AC input power to DC power supply, the rectifier circuit having at least four unidirectional components, namely the first, second, third and fourth unidirectional components 315 . 316 . 317 . 318 , wherein the positive terminal of the first and third unidirectional component 315 . 317 each with the first and second AC input terminals 311 . 312 is connected, wherein the negative terminal of the first and fourth unidirectional component 315 . 318 each with the second rectifier output terminal 314 is connected, wherein the negative terminal of the second and third unidirectional component 316 . 317 each with the first rectifier output terminal 313 connected is. The above-mentioned unidirectional components may be rectifier diodes or light-emitting diodes.

The first LED module 510 is between the negative terminal of the first unidirectional component 315 and the positive terminal of the second unidirectional component 316 connected. The first LED module 510 may comprise a single light emitting diode or a plurality of light emitting diodes or it may be connected in series with a plurality of light emitting diodes, as shown in the figure.

The second LED module 610 is between the negative terminal of the third unidirectional component 317 and the positive terminal of the fourth unidirectional component 318 connected. The second LED module 610 may comprise a single light emitting diode or a plurality of light emitting diodes or it may be connected in series with a plurality of light emitting diodes, as shown in the figure.

The multi-level driver module 710 is between the positive terminal of the second unidirectional component 316 and the positive terminal of the fourth unidirectional component 318 connected. Here, the multi-stage driver module 710 a multi-stage drive unit or a current limiting unit, wherein the multi-stage driver module 710 may be provided with a first and second input terminal S1, S2, wherein the first input terminal S1 between the first LED module 510 and the positive terminal of the second unidirectional component 316 is connected, wherein the second input terminal S2 between the second LED module 610 and the positive terminal of the fourth unidirectional component 318 is switched, wherein the multi-stage driver module 710 several lighting voltages can be set in different stages. In the present embodiment shown in the figure, a lighting voltage in the first stage and a lighting voltage in the second stage are respectively set.

(See at the same time 4 ) By increasing the input voltage 810 is in an AC cycle on the first LED segment 510 and on the second LED segment 610 successively establishing an electrically conductive connection whereby the first and second segments are illuminated, the first and second LED modules 510 . 610 if an electrically conductive connection is made in the positive half cycle or in the negative half cycle, lighting in a different order. When in the positive half cycle an electrically conductive Connection is made and the input voltage 810 is increased to the lighting voltage in the first stage, the first input terminal S1 starts to operate, and the LED drive current flows through the first input terminal S1, at which time the first LED module 510 an electrically conductive connection is made, whereby this lights up. When the input voltage 810 is further increased such that the voltage drop of the first input terminal S1 relative to the second input terminal S2 reaches the lighting voltage in the second stage, at this time, the LED drive current flows through the second input terminal S2 and the first input terminal S1 is closed, at which time at the first and second LED module 510 . 610 an electrically conductive connection is made, whereby these two light up. In the opposite case, the second LED module work 610 and the first LED module 510 with the decrease of the input voltage 810 when the voltage drops below the lighting voltage of all stages, one after another no longer. Because at the flow path of the positive half-cycle the first LED module 510 Priority is assigned in the process of continuous increase in voltage first at the first LED module 510 and then the second LED module 610 made an electrically conductive connection, whereby these two shine one after the other.

At the flow path of the negative half cycle becomes the second LED module 610 Assigned priority. When the input voltage 810 is increased to the lighting voltage in the first stage, the second input terminal S2 starts to operate and the LED current flows through the second input terminal S2, at which time the second LED module 610 an electrically conductive connection is made, whereby this lights up. When the input voltage 810 is further increased such that the voltage drop of the second input terminal S2 with respect to the first input terminal S1 reaches the lighting voltage in the second stage, at this time the LED current flows through the first input terminal S1 and the second input terminal S2 is closed, at which time at the second and first LED module 610 . 510 an electrically conductive connection is made, whereby these two light up. Because at the flow path of the negative half cycle the second LED module 610 Priority is assigned in the process of continuous increase in voltage first at the second LED module 610 and then the first LED module 510 made an electrically conductive connection, whereby these two shine one after the other.

In this embodiment, in the flow path of the positive half cycle and the negative half cycle, all the LED modules are lit in a different order. This corresponds exactly to what is defined in the present invention, namely that "all LED modules, if in the positive half-cycle or in the negative half-cycle an electrically conductive connection is made, shine in a different order". From the 4 It can be seen that in the cycle time of the AC, the power and brightness of the first and second LED modules are consistent, thereby significantly reducing the problem of uneven brightness between different LED modules in an ordinary multi-stage driver. Whether the performance of the first and second LED modules are consistent in the AC cycle time can be determined by the following calculation formula:
In the 2 and 4 V1, -V1 represent the lighting voltages in the first stage. V2, -V2 represent the lighting voltages in the second stage. The period from 0 to t1 represents the lighting voltages that did not reach the first stage. The periods of t1 to t2, from t3 to t4, from t5 to t6, and from t7 to t8, the illumination voltages that have reached the first stage represent the times of these periods being the same, ie, T1 = | t1 - t2 | = | t3 - t4 | = | t5 - t6 | = | t7 - t8 |. The periods from t2 to t3 and from t6 to t7 represent the illumination voltages that have reached the second stage, the times of these periods being equal, ie, T2 = | t2 - t3 | = | t6 - t7 |.

In the in 2 In the conventional driving circuit shown, in one AC cycle, the powers of the two luminous LED segments are S01, S02, respectively. I1 is the drive current value when V1 is the lighting voltage and I2 is the drive current value when V2 is the lighting voltage, here: S01 = I1 × V1 × 4T1 + I2 × V1 × 2T2 S02 = I2 × (V2-V1) × 2T2 (Formula 1) assuming that V2 = 2V1 S02 = I2 × V1 × 2T2 (formula 2) The subtraction of Formula 1 and Formula 2 is (I1 x V1 x 4T1). This shows that S01 is greater than S02, ie the powers of the two luminous LED segments 121 . 122 are still different, so there is a difference in brightness between the two LED segments 121 . 122 is present.

Compared to 4 in an AC cycle, the power of the first and second LED modules are S03, S04, respectively. I1 is the drive current value when V1 is the lighting voltage and I2 is the drive current value when V2 is the lighting voltage, here: S03 = I1 × V1 × 2T1 + I2 × V1 × T2 + I2 × (V2-V1) × T2 (Formula 3) S04 = I2 × (V2-V1) × T2 + I1 × V1 × 2T1 + I2 × V1 × T2 (Formula 4) Formula 3 and Formula 4 are the same, which means that S03 and S04 are the same, ie the luminous first LED module's power and the luminous second LED module's power are the same, and the brightness of the first LED module and the brightness of the first LED module second LED module are the same, so there is no visible difference in brightness to the human eye.

(Please refer 5 ) The first LED module 510 is further provided with a first capacitor unit 520 connected in parallel and the second LED module 610 is further with a second capacitor unit 620 connected in parallel, creating the first capacitor unit 520 and the second capacitor unit 620 each the rectified AC voltage output in the first LED module 510 and the rectified AC voltage output in the second LED module 610 can adjust. In the charging phase, the LEDs are driven by the rectified alternating current and at the same time become the first and second capacitor unit 520 . 620 loaded. In the discharge phase, the first and second LED module 510 . 610 respectively through the first and second capacitor units 520 . 620 powered to produce a stable DC voltage, so that the first and second LED module 510 . 610 in the best working range, thereby improving the flicker phenomenon without compromising the current harmonics and performance factors of the driving circuit of the LED modules. Furthermore, in the present invention, the capacitor units are each connected in parallel with the corresponding LED modules, the voltage resistance value of the respective capacitor unit being dependent on the number of LED modules connected to the driver, ie the greater the number of connected LED modules, the lower the voltage resistance value of the respective capacitor unit. The withstand voltage value of the capacitors used may be less than 100 volts. In the present embodiment, 20 to 50 volt low voltage capacitors may be used, which are less expensive and smaller.

As is known to those skilled in the art, the phenomenon of flickering is subject to cyclical changes which may be determined by the amount of change in amplitude, average level, periodic frequency, shape and / or duty cycle of its waveform. To quantify flicker, flicker in percent and flicker index are typically used. In order to more fully illustrate the advantageous effect of the present invention, the data obtained by the measurements made in the present invention and the measurements made in the conventional linear driver are listed below, wherein the measurement performed by United Power Research Technology Corp. was performed , hand-held spectrometer (model number MF205N) was used: conventional single-stage linear driver conventional six-stage linear driver inventive driver Flimmerindex 0.4 0.25 0.05 Flicker in percent (%) 99 99 17 Visibility measure of the stroboscopic effect 4.1 2.8 0.5 Frequency (Hz) 120 120 120 Table 1 conventional single-stage linear driver conventional six-stage linear driver inventive driver Flimmerindex 0.68 0.42 0.06 Flicker in percent (%) 99 99 25 Visibility measure of the stroboscopic effect 6.2 5.9 0.68 Frequency (Hz) 120 120 120 Table 2

In the above data measured by hand spectrometer, Table 1 shows the measurement results obtained with the triac dimmer when setting a brightness of 100%, and Table 2 shows the measurement results obtained with this dimmer when setting a brightness of 20%. The lower the flicker percentage and flicker index, the less visible the flicker phenomenon is. Stroboscopic Effect Visibility Measurability is a method of quantifying the visibility of high frequency flicker with a frequency range of 80 Hz to 2000 Hz, a sampling time of at least 1 s and a sampling rate of at least 4000 1 / s. In this method, a fast Fourier transformation (FFT Fast Fourier Transformation) is performed on the measured light output curve and then calculated together with the frequency response function for the human eye. Visibility measure of the stroboscopic effect = 1: faintly visible; Visibility of the stroboscopic effect <1: not visible; Visibility of the stroboscopic effect> 1: clearly visible. From the above measurement data, it can be seen that the flicker index, the flicker percentage, and the visibility measure of the stroboscopic effect of the present invention are the lowest when the dimmer sets the brightness to 100% and 20%, and the visibility amount of the stroboscopic effect is <1. Thus, the present invention has the least flicker. In addition, the new Lighting Act, which was introduced in California, USA, includes a new specification for the flicker of light sources when setting the brightness to 100% and 20% through a dimmer: if the flicker frequency is below 200 Hz, that must Flicker percentage less than 30%. It can be seen from the above measurement data that only the driver according to the invention is able to fulfill this specification.

Im in 6 embodiment shown, the present invention may also be provided with a plurality of multi-stage driver modules, such. B. two multi-stage driver modules 710 . 720 , which are each provided with a first and second input terminal S1, S2, wherein the first input terminal S1 of the multi-stage driver module 710 between the second LED module 610 and the positive terminal of the fourth unidirectional component 318 is switched, wherein the second input terminal S2 between the first LED module 510 and the positive terminal of the second unidirectional component 316 is switched, wherein the first input terminal S1 of the other multi-stage driver module 720 between the first LED module 510 and the positive terminal of the second unidirectional component 316 is connected, wherein the second input terminal S2 between the second LED module 610 and the positive terminal of the fourth unidirectional component 318 is switched. In this way, multi-stage driving can also be achieved, and in the cycle time of the AC power, the power and brightness of the first and second LED modules can be consistent.

In the present invention, the number of LED modules can be increased. Furthermore, at least one further LED module and at least one further unidirectional component can be added. Im in 7 embodiment shown is a third LED module 910 added. In the rectifier circuit are two unidirectional components, namely the fifth and sixth unidirectional components 920 . 930 , added. In the rectifier circuit is a third rectifier output terminal 940 added. The multi-level driver module 710 is provided with a third input terminal S3. In the present embodiment, the first, second, and third LED modules, when electrically conductive in the positive half cycle or negative half cycle, are also illuminated in a different order, and the power and brightness of all the LED modules are consistent in the cycle time of the AC current so that there is no visible difference in brightness to the human eye.

In the present invention, the LED modules may each be further connected in parallel with a capacitor unit, as in FIG 8th shown. The above-mentioned at least one further added LED module is also connected in parallel with another capacitor unit. The first, second and third LED module shown in the embodiment and in the figure 510 . 610 . 910 is in each case with the first, second and third capacitor unit 520 . 620 . 950 connected in parallel. The first, second, and third LED modules, when electrically conductive in the positive half cycle or negative half cycle, also shine in a different order, and the power and brightness of all the LED modules are consistent in the cycle time of the AC current, thus there is no visible difference in brightness for the human eye. The condenser units can achieve an improvement in the phenomenon of flicker without affecting the current harmonics and power factors of the original driver modules of the LED modules.

In the present invention, a flow path of the positive or negative half-cycle of the alternating current is thus provided by at least two unidirectional components, wherein in each case in the flow path of the positive or negative half cycle at least two LED modules are integrated and further a multi-stage driver module is integrated the at least two LED modules, when establishing an electrically conductive connection in the positive half-cycle or in the negative half-cycle, light in a different order so that in the cycle time of the alternating current the power and brightness of the at least two LED modules can be consistent thereby To significantly reduce the problem of uneven brightness between different LED modules in a common multi-stage driver.

LIST OF REFERENCE NUMBERS

DR1, DR2

input port

I1, I2

LED current

S1

first input connection

S2

second input connection

S3

third input connection

110

Bridge rectifier

LED 121

first LED segment

LED 122

second LED segment

IC140

multi-level linear driver

210, 810

input voltage

311

first AC input connection

312

second AC input connector

313

first rectifier output terminal

314

second rectifier output terminal

315

first unidirectional component

316

second unidirectional component

317

third unidirectional component

318

fourth unidirectional component

510

first LED module

520

first capacitor unit

610

second LED module

620

second capacitor unit

710

multi-level driver module

720

multi-level driver module

910

third LED module

920

fifth unidirectional component

930

sixth unidirectional component

940

third rectifier output terminal

950

third capacitor unit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• TW 201104915 A [0005]

Claims (8)

An LED driver, at least comprising: a rectifier circuit comprising a first AC input terminal, a second AC input terminal, a first rectifier output terminal and a second rectifier output terminal, the first and second AC input terminals for receiving an AC input power, the rectifier circuit having at least four unidirectional components, namely, the first, second, third, and fourth unidirectional components, wherein the positive terminals of the first and third unidirectional components are respectively connected to the first and second AC input terminals, the negative terminals of the first and fourth unidirectional components being respectively connected to the first and second unidirectional components the second rectifier output terminal is connected, the negative terminal of the second and third unidirectional components being connected to the first rectifier output terminal, respectively; a first LED module connected between the negative terminal of the first unidirectional component and the positive terminal of the second unidirectional component; a second LED module connected between the negative terminal of the third unidirectional component and the positive terminal of the fourth unidirectional component; and a multi-stage driver module connected between the positive terminal of the second unidirectional component and the positive terminal of the fourth unidirectional component. The LED driver of claim 1, wherein the multi-stage driver module has at least two input terminals, one of these input terminals being connected between the first LED module and the positive terminal of the second unidirectional component and the other input terminal being connected between the second LED module and the positive LED Connection of the fourth unidirectional component is connected. The LED driver of claim 1, wherein the multi-stage driver module is a multi-stage drive unit or a current limiting unit. LED driver according to one of claims 1 to 3, wherein at least one further LED module and at least one further unidirectional component is added to the LED driver. The LED driver of claim 4, wherein the first LED module is further connected in parallel with a first capacitor unit and the second LED module is further connected in parallel with a second capacitor unit. LED driver according to claim 4, wherein the at least one further added LED module is connected in parallel to each other with a different capacitor unit. The LED driver of claim 6, wherein the withstand voltage value of the capacitor units is less than 100 volts. The LED driver of claim 4, wherein the unidirectional components are rectifier diodes or light emitting diodes.

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